Furnace stoker



J. S.I BENNETT FURNACE STOKER original Filed oct. 23', 1954 2 Sheets-ShamI l J. S. BENNETT FURNACE STOKER Nov. 8, 1938.

Original Filed Oct. 23, 1934 2 Sheets-Sheet 2 If? @afar Patented Nov. 8, 1938 FURNACE STOKER Joseph S. Bennett, Merion, Pa., assgnor to American Engineering Company, Philadelphia, Pa.,

a corporationrof Pennsylvania original application october 23, i934, serial No. 749,539. Divided and this application Septem ber 22, 1937, serial Np. 165,057

10 Claims. (Cl. 122-4) This application is a division of my co-pending application Ser. No. 749,539, filed October 23, 1934, and the inventionhere involved relates to stoker furnaces, and more particularly to stokers having fluid cooling means associated therewith for preventing clogging of the tuyre openings by slag and clinker formations. The ash content of certain types of coals, it has been found, not-only fuses at a comparatively low temperature, but forms an impervious mass when cooled which clogs the air openings of the grates as well as impairs the operation of the stoker as a whole. In many cases it is necessary to extinguish the re at frequent intervals so that the slag and clinker masses adhering to the grates may be removed.

One object of the present invention is to provide means for preventing such damage to the grates and to insure'efcient burning of all fuels.

v lAnother object is to provide in an underfeed A further object is to provide a stoker of the continuous ash discharge type wherein the entire exposed surface thereof is effectively cooled by fluid conducting means.

Other'and further objects will become apparent as Vthe description of the invention progresses.

Of the drawings:

`Fig. 1 is a longitudinal sectional View taken through a furnace, showing one type of fluid `cooled stoker of the continuous ash discharge type. g

Fig. 2 is a plan view taken substantially along line 2 2 of Fig. 1, and r Fig. 3 is a longitudinal sectional View of a stoker of a modified construction.

Referring to the drawings, the numeral l designates a furnace having provided therein an underfeed stoker 2, comprising alternately disposed retorts 3 and tuyre rows 4. Fuel is fed into the retorts 3 from hoppers 5 by any suitable feeding 1145 mechanism, partially indicated at 6, and operated by any suitable power mechanism (not shown). The fuel entering the retorts 3 is underfedl over the length thereof by pushers' 8, and the extension grates 9 provided at the rear end of the sto-ker overfeed the fuel through a discharge opening provided in the rear or bridge wall i3 of the furnace. As shown in Figs. 1 and 2, a series of fluid conducting tubes 25 are, mounted on the tuyere blocks of each of the tuyre rows l ll. The upper ends of tubes 25 extend vertically a short distance adjacent the front wall of the furnace and terminate in a header 26 suitably supported in said wall. These vertical extensions of the tubes cool the portions of the wall adjacent the inlet passages to the retorts and 5 minimize the formation and growth of clinkers thereon. The lower ends of tubes 25 continue downwardly at a slightly steeper angle and are disposed in cooling relation with a series of fixed extension grates 31; the movable extension grates 10 9 being in alignment only with the retorts and thus are not in contact with the tubes. The tubes 25 terminate at the lower ends thereof in a header 35 supported in any suitable manner beneath extension grates 9 and 31. Connected 15 to and extending rearwardly of header 35 are a series of tubes 38, the substantially horizontal portions 38 of which form a shelf which receives the consumed'fuel fed from the extension grates 9 and 31, while the substantially vertical 20 portions 38 thereof are connected at their lower ends to a header 39 mounted in any suitable manner upon a support 49. The bridge wall 13, as shown in Fig. 1, terminates above the tubes 38 and has provided 'therein a series of fluid con- 25 ducting tubes I4. 'I-'he'lower ends I4 of these tubes form the exposed surface of the upper wall of passage 4l, and terminate in a header I6. The tubes lll are bent, as shown at 14, and extend upwardly and form the exposed surface of bridge 30 wall I3. The upper ends of these tubes may be connected to a header, or directly to a boiler (not shown). Headers E8 and 39 are connected to the boiler by downcomer connections I6' and 39 respectively, while header 26 is connected to said 35 boiler by riser connection 2BA.

Fig. 3 shows a construction somewhat on the order of that shown in Figs. 1 and 2, except that the tubes 25' provided on tuyre rows 4' extend rearwardly of the stoker, as shown at 38A, 40 forming a portion of a shelf which receives the residue fed from the stoker. lIn this construction the extension grates 9 and 31, shown in Figs.

1 and 2, are dispensed with, and the lower ends of tubes 25 terminate in a header 39A supported 45 at Gil. A header 35 is supported in any suitable manner beneath the lower end of the stoker, which receives the upper ends of an alternately disposed series of tubes 42 disposed in substantial alignment with the retorts 3. These tubes 50 extend in parallel relation with the extended portions 39A of tubes 25' and also terminate at their lower ends in header 39A. In this construction a series of refractory elements 53 are secured to tubes 25 and 42, as shown in Fig. 3. These ele- 55 ments are mounted in spaced relation, forming openings therebetween through which draft air may pass, as indicated by the arrows in Fig. 3. The plenum chamber beneath the stoker is divided into compartments 44 and 45 by a wall 46. Air enters chamber 44 through an inlet passage 41, a portion of Iwhich may pass into chamber 45 through the opening 48 provided in wall 4B. The amount of air flowing into compartment 45 may be regulated by a damper 49 operated'wby a rod 50. Under certain conditions it maybe desirable to provide pressure means to cause a more rapid circulation offluid inthe tubes '25- and 42 of the stoker. To this end a booster pump Il is provided which, as shown in Fig. 3, is connected to the boiler (not shown) byva-downtake connection |02 and feeds fluid underpressure to header 39A through pipe |03. Headers V35 and 26 are connected to the boiler by riser connections 35A and 28B, respectively. The substantially horizontal section 38Ais spaced from the lower endl of bridge wall I3', thus providing a passage 4l through -which the refuse from ythe stoker is fed. The exposed surface of bridge wall I3 also has provided thereina series of fluid conducting tubes 14A which extend forwardly and upwardlyfrom a header IBA. The upper ends of tubes UiA may be connected to a header or directly to one of the steam drums ofra boiler (not shown).

The constructions herein shown and described not only lower the maintenance cost of stokers,

-but permit furnaces to operate for long-periods ofk time without interruption. These constructions are especially desirable when the fuels burned are ofthe type wherein the ash content thereof fuses -at low temperatures.Y This molten vash has a tendency to clog-the tuyre openings,

and thus prevents the proper amount of air to enter the fuel bed. This also-causes-considerable damage to the grates with the result that the maintenance cost is not only high, but-a considerable loss is experienced in taking the boilers off the line to make the necessary repairs. The con- .structions herein shown havelargely eliminated these undesirable conditions andfhave also increased the efficiency of the units as well.

While the invention is shown applied to stokers ofthe underfeed type, it is believed tobe apparentthat it is equally adaptable for use in other types of stokers as well. The invention therefore is not to be limited to the embodiments herein shown since it may be embodied in other forms, all coming within the scope Aof claims which follow.

What is claimed is:

l. In a furnace, the combination of :a rear'wall having a transverse recess provided at the lower end thereof, a front wall, a stoker inclining downwardly and rearwardly from said front wall, a longitudinal extension provided at the rearwardly disposed end of said Stoker, said extension extending into the recess provided in said rear wall and forming with the lower end of the latter a passage, and means for fluid cooling said stoker and rear wall.

2. In a furnace, the combination of a rear wall having a transverse recessprovided at the lower end thereof, a front wall, a stoker inclining downwardly and rearwardly from said front wall, said AStoker consisting of alternately disposed retorts and tuyre rows, an extension provided at the lower end of said Stoker and extending into the recess provided in said rear wall, said extension being disposed in spaced relation with the lower end of said rear `wall and forming therewith a passage, said extension comprising a series of fluid conducting tubes, and means comprising a series of fluid conducting tubes mounted on the exposed surfaces of said rear wall.

3. In a furnace, the combination of a rear wall having a transverse recessprovided at the lower end thereof, a front wall, a stoker inclining downwardly and rearwardly from said front wall, said .stoker consisting of alternately disposed retorts and tuyre rows, an extension provided at the lower end of said stoker and extending into the -recess providedin said rear wall, said extension being'disposed in spaced relation with the lower end of said rearwall and forming therewith a passage,y said extension comprising a series of fluid conducting tubes, means comprising one or lmore tubes mounted in cooling relation with said tuyre rows, headers connecting the opposite ends of said tubes, and means comprising a series of fiuidA conductingtubesmounted on the exposed surface of said rearwall.

4. In an underfeed stoker, comprising alternately disposed retorts and tuyre rows,.of alternately disposed fixed and moving extension grates mounted at the rear end of said retorts and tuyre rows, fluid conducting tubes mounted over said tuyre rows and fixed extension grates, upper and lower headers for receivingthe opposite endsv of said tubes, a second series of liuid f conducting tubes connected to and extending rearwardly of said lowerheader forming a` shelf for supporting the fuel fed by said extension grates, and a series of fluid conducting tubes provided above and in spaced relation with said shelf 5 forming therewith a passage through which .the fuel discharging from said` Stoker may pass.

5. `In an underfeed` stoker, comprising alternately disposed retorts and tuyre rows, of means for feeding fuel to said retorts and tuyre rows,

one or more fluid conducting tubes mounted over each tuyreV row, the lower ends of said tubes extending rearwardly forming a support for the fuel fed from said stoker, said tubes terminating at their' lower ends in a header, a second header for the upper ends of said tubes, a third header disposed near the lower end of said retorts and tuyre rows, a series of tubes extending rearwardly of said header and inparallel relation with theV extensions ofv said first mentioned. tubes, .i

and terminating in said header first named, and a series of fluid cooled tubes mounted above and in spaced relation with said support and forming therewith a discharge passage for ther fuel discharging from the stoker.

6.In an underfeed stoker, comprising alternately disposed retorts and tuyre rows, of means for feeding fuel to said retorts-and rows of tuyres, one or more fluid connecting tubes mounted in `cooling relation with the tuyres of each of said rows, the lower ends of said tubes extending rearwardly and forming a support for. the fuel Vnately disposed retorts and rows of tuyre .blocks of means for feeding fuel to said retorts and rows of tuyre blocks, one or more fluid conducting tubes mounted in cooling relation with the tuyre blocks of each of said rows, the lower ends of said tubes extending rearwardly, forming a support for the fuel fed from said stoker, said tubes terminating at their lower ends in a header, a second header for the upper ends of said tubes, a third header disposed near the lower ends of said retorts and tuyre rows, a series of tubes extending rearwardly of said header and in parallel relation with the extensions of said first mentioned tubes and terminating in said header rst named, a boiler, means for connecting said headers to said boiler, and a booster pump for feeding fluid under pressure from said boiler to one of said headers.

8. In an underfeed stoker, comprising alternately disposed retorts and rows of tuyre blocks, of alternately disposed, fixed and movable extension grates mounted at the rear end of said retorts and rows of tuyre blocks, one or more fluid conducting tubes mounted in cooling relation with the tuyre blocks of each of said rows and said fixed extension grates, upper and lower headers connecting the opposite ends of said tubes, a second series of fluid conducting tubes connected to and extending rearwardly of said lower header forming a shelf for supporting the fuel fed by said extension grates, a header connecting the other end of last last mentioned tubes, and means for supplying fluid to said last mentioned header.

9. In an underfeed Stoker, comprising alternately disposed retorts and rows of tuyre blocks, of alternately disposed xed and movable extension grates mounted at the rear end of said retorts and rows of tuyre blocks, one or more iuid conducting tubes mounted in cooling relation with the tuyre blocks of each of said rows and. said xed extension grates, upper and lower headers for receiving the opposite ends of said tubes, a series of fluid conducting tubes connected to and extending rearwardly of Isaid lower header forming a shelf for supporting the fuel fed by said extension grates, and a series of iluid conducting tubes provided above and in spaced relation with said shelf forming therewith a passage through which the fuel discharging from said stoker may pass.

10. In a furnace, the combination of a rear wall having a transverse recess provided at the lower end thereof, a front wall, a stoker inclining downwardly and rearwardly from said front wall, a longitudinal extension provided at the rearwardly disposed end of said Stoker, said extension being disposed beneath the lower end of said rear wall and forming therewith a passage, and means for uid cooling said Stoker.

JOSEPH S. BENNETI. 

